President Donald Trump is doubling down on wielding economic pressure to squeeze Iran as his military options dwindle, and Tehran’s business community warned the naval blockade will cause far-reaching harm.

In an interview with Iran’s Khabar Online outlet, the head of the Iran-China Joint Chamber of Commerce said “the consequences of the blockade far outweigh those of a direct war.”

Majidreza Hariri added that the economic crisis and shortages currently ravaging Iran under the blockade are more severe than they were during the 40-day war earlier this year.

As a result, Iran must find a way to end the blockade one way or another, whether by way of negotiations, pleading, threats or even renewing war against the U.S., he said. That’s because trying to cope with the blockade would lead to dangerous spillover effects.

“The worst thing that could happen today is believing that the naval blockade can be circumvented and attempting to govern the country despite its continuation,” Hariri said.

He pointed to Iran’s decades-long experience under Western sanctions, saying the methods that were used skirt them eventually resulted in a weak economy and rampant corruption.

The U.S. naval blockade also threatens to inflict enormous costs in the short term. For example, transporting a single container between Iran and China via ships costs about $3,000, according to Hariri. But bypassing the blockade by transporting it over land would boost the cost to $12,000.

Given that 2 million containers pass through Iran’s southern ports annually, he estimated that heavier trade burdens will translate to about $18 billion in additional transportation costs alone every year.

Relying on land routes to get around the blockade could provide enough necessities to allow for short-term survival, but the economy will eventually “grind to a halt,” Hariri predicted.

But he also suggested Iran would retaliate against continued U.S. pressure rather than simply standing by and watching the economy crumble.

“We must also eliminate the perception in the U.S. that it can resort to such an action whenever it wants, and make it understand that the consequences of such a move could be severe,” Hariri said.

His warning comes as regime moderates have grown more worried that the U.S. naval blockade that was recently reimposed is bringing Iran’s economy close to collapse, sources told the Wall Street Journal.

Iran’s deputy foreign minister has also said the economy desperately needs sanctions relief that a deal with the U.S. could provide.

That tracks with earlier reports about Iran’s president and central bank chief telling Supreme Leader Ayatollah Mojtaba Khamenei the initial blockade was crippling the economy.

High inflation and a currency crash triggered widespread protests that led to a brutal crackdown in January, and some officials in Tehran are concerned today’s economic woes could stir more unrest.

But experts have cautioned that Iran’s repressive regime is unlikely to be swayed by the suffering of ordinary citizens and is prepared to wait out economic hardship longer than the U.S. public can endure high gas prices.

Still, Trump is betting that the blockade can accomplish what intense bombing from the U.S. military failed to do, namely, forcing Iran to reopen the Strait of Hormuz.

At the same time, a significant volume of oil is sneaking out of the Persian Gulf, contradicting Iran’s claims that it has closed off the strait, while the blockade is also denying Tehran vital oil revenue.

Crude prices have come down from last month’s highs, and the oil market reprieve gives Trump more time to let his blockade play out. Meanwhile, even more pressure could be on the way.

“It will be a combination of economic isolation like ‌the world has ​never seen before, ​and ​the continued blockade in ‌the Strait of ​Hormuz that will ​keep anything from going in or out of ​the ‌Iranian ports,” Treasury Secretary Scott Bessent told Newsmax without elaborating.

This story was originally featured on Fortune.com